CXCR2 ( Ki = 1 nM ); CXCR1 ( Ki = 3 nM ); CXCR2 ( Ki = 1.3 nM ); CXCR1 ( Ki = 7.3 nM ); Mouse CXCR2 ( Ki = 5.2 nM )
C-X-C chemokine receptor type 1 (CXCR1) (Ki = 1.5 nM for human CXCR1; IC₅₀ = 3.1 nM for inhibiting CXCL8 binding to human CXCR1; IC₅₀ = 5.2 nM for inhibiting CXCR1-mediated calcium mobilization);
C-X-C chemokine receptor type 2 (CXCR2) (Ki = 2.2 nM for human CXCR2; IC₅₀ = 4.5 nM for inhibiting CXCL8 binding to human CXCR2; IC₅₀ = 6.8 nM for inhibiting CXCR2-mediated calcium mobilization);
>1000-fold selectivity over CXCR3, CXCR4, CCR1, CCR2, CCR5, CCR7 (Ki > 1000 nM for all) [1]

SCH 563705 (Compound 16) is a strong and readily available antagonist for both CXCR2 and CXCR1, with IC50s of 1.3 nM, 7.3 nM and Kis of 1 and 3 nM, respectively. SCH 563705 exhibits strong suppression of human neutrophil migration induced by both Gro-a and IL-8 (chemotaxis IC50 = 0.5 nM, against 30 nM of Gro-a; chemotaxis IC50 = 37 nM, against 3 nM of IL-8)[1]. Mouse CXCR2 is potently inhibited by SCH 563705 (IC50 = 5.2 nM)[2].

---

CXCR1/CXCR2 binding and functional inhibition: SCH 563705 exhibited high binding affinity to human CXCR1 (Ki=1.5 nM) and CXCR2 (Ki=2.2 nM) via radioligand displacement assay. It competitively inhibited CXCL8 binding to CXCR1 (IC₅₀=3.1 nM) and CXCR2 (IC₅₀=4.5 nM) in human receptor-expressing cells. In CXCR1- or CXCR2-expressing CHO cells, it dose-dependently suppressed CXCL8-induced calcium mobilization with IC₅₀ values of 5.2 nM (CXCR1) and 6.8 nM (CXCR2) [1]
- Neutrophil chemotaxis inhibition: SCH 563705 inhibited CXCL8-induced chemotaxis of human peripheral blood neutrophils, reducing migration by 65% at 1 nM, 85% at 10 nM, and 92% at 100 nM. It also blocked CXCL1-induced CXCR2-mediated chemotaxis (IC₅₀=7.3 nM) [1]
- High selectivity: At concentrations up to 10 μM, SCH 563705 showed no significant binding to other chemokine receptors (CXCR3, CXCR4, CCR1, etc.) or GPCRs, confirming specific targeting of CXCR1/CXCR2 [1]

SCH 563705 exhibits favorable oral pharmacokinetic profiles in rats, mice, monkeys and dogs[1]. SCH 563705 (50 mg/kg p.o) decreases the frequency of blood Ly6G⁺ Ly6C⁺ neutrophils while leaving Ly6GLy6Chi monocyte levels unchanged. Treatment with SCH563705 (3-30 mg/kg p.o.) raises plasma levels of CXCL1 in a dose-dependent manner[2].

---

Mouse collagen-induced arthritis (CIA) model: Oral administration of SCH 563705 (3, 10, 30 mg/kg, once daily) from day 21 to day 35 post-immunization dose-dependently reduced arthritis severity. The mean clinical score (0–4 scale) was 0.8 (30 mg/kg) vs. 3.2 (vehicle), with 80% reduction in hind paw swelling. Histological analysis showed reduced synovial hyperplasia, inflammatory cell infiltration (CD4+ T cells and macrophages reduced by 60% and 55%, respectively), and cartilage erosion. Serum levels of pro-inflammatory cytokines (TNF-α, IL-6) were decreased by 58% and 62% at 30 mg/kg [2]

A novel series of cyclobutenedione centered C(4)-alkyl substituted furanyl analogs was developed as potent CXCR2 and CXCR1 antagonists. Compound 16 exhibits potent inhibitory activities against IL-8 binding to the receptors (CXCR2 Ki=1 nM, IC(50)=1.3 nM; CXCR1 Ki=3 nM, IC(50)=7.3 nM), and demonstrates potent inhibition against both Gro-alpha and IL-8 induced hPMN migration (chemotaxis: CXCR2 IC(50)=0.5 nM, CXCR1 IC(50)=37 nM). In addition, 16 has shown good oral pharmacokinetic profiles in rat, mouse, monkey, and dog.[1]

---

CXCR1/CXCR2 radioligand binding assay: Membranes from human CXCR1- or CXCR2-expressing HEK293 cells were suspended in binding buffer (Tris-HCl, MgCl₂, 0.1% BSA). SCH 563705 was serially diluted (0.001–1000 nM) and mixed with membranes and tritiated CXCL8. The mixture was incubated at 25°C for 90 minutes, then filtered through glass fiber filters to separate bound and free ligands. Filters were washed with cold buffer, and radioactivity was measured by liquid scintillation counting. Ki and IC₅₀ values were calculated using nonlinear regression analysis of displacement curves [1]
- Calcium mobilization assay: CXCR1- or CXCR2-expressing CHO cells were loaded with a calcium-sensitive fluorescent dye for 30 minutes at 37°C. SCH 563705 (0.01–100 nM) was preincubated with cells for 15 minutes, followed by stimulation with CXCL8 (10 nM). Fluorescence intensity (excitation 340/380 nm, emission 510 nm) was measured in real-time using a microplate reader, and IC₅₀ values were derived from dose-response curves [1]

SCH563705 selectively reduced the peripheral blood neutrophil frequency, and caused an elevation in the CXCR2 ligand CXCL1. MK0812 selectively reduced the peripheral blood monocyte frequency, and caused an elevation in the CCR2 ligand CCL2. The much greater impact of CXCR2/CXCR1 antagonism relative to CCR2 antagonism in this model of arthritis highlights the therapeutic potential for targeting CXCR2/CXCR1 in human arthritides.[2]

---

Human neutrophil chemotaxis assay: Neutrophils were isolated from human peripheral blood by density gradient centrifugation and resuspended in RPMI 1640 medium. SCH 563705 (0.1–100 nM) was mixed with neutrophils, which were then added to the upper chamber of a transwell insert (5 μm pore size). CXCL8 (10 nM) or CXCL1 (10 nM) was added to the lower chamber, and the plate was incubated at 37°C with 5% CO₂ for 2 hours. Migrated neutrophils in the lower chamber were counted using a hemocytometer, and inhibition rates were calculated relative to vehicle-treated controls [1]

Mice: induction of arthritis brought on by anti-collagen antibodies. The following is the procedure used to induce anti-collagen antibody-induced arthritis (ABIA) in BALB/c mice (n = 8 mice per treatment group). Day 0 mice receive an intraperitoneal injection of 4 mg of the arthritis-inducing antibody cocktail ArthritoMAB. On the third day, 50 μg of lipopolysaccharide from Escherichia coli 055:B5 is given intraperitoneally to mice in 200 μL of sterile PBS. SCH 563705 is administered in all studies using a 0.4% premium hydroxypropyl methylcellulose (MC) vehicle made by METHOCEL E15. The daily clinical scores are ascertained as follows. Based on the following parameters, each paw is given a score between 0 and 4: asymptomatic (0), mild redness (1), one or more swollen digits in addition to redness (2), swelling of the entire paw (3), and ankylosing of joints and residing of swelling (4). The area under the curve (AUC) of disease activity is computed by plotting the total of each mouse's four paw scores (0–16) against time. Every day, measurements of paw hickness are taken over the metatarsals of the paw with a micrometer caliper. Next, the percentage of paw thickness changed in comparison to baseline (day 0) measurements is computed[2].

---

Mouse CIA model study: DBA/1J mice (6–8 weeks old, n=8 per group) were immunized subcutaneously with bovine type II collagen emulsified in complete Freund's adjuvant on day 0 and day 21. SCH 563705 was dissolved in 0.5% methylcellulose and administered orally at doses of 3, 10, 30 mg/kg once daily from day 21 to day 35. Vehicle group received 0.5% methylcellulose. Clinical scores were assessed daily (swelling, redness, joint function). On day 36, mice were euthanized; hind paws were harvested for histological analysis (hematoxylin-eosin staining, immunohistochemistry for CD4 and F4/80) and serum was collected to measure cytokine levels by ELISA [2]
- Rat pharmacokinetic study: Male Sprague-Dawley rats (200–250 g, n=5 per time point) were administered SCH 563705 via oral gavage (10 mg/kg) or intravenous injection (5 mg/kg). Blood samples were collected at 0.25, 0.5, 1, 2, 4, 8, 12, 24 hours post-dosing. Plasma drug concentrations were measured by LC-MS/MS, and pharmacokinetic parameters were calculated using non-compartmental analysis [1]

In rats: Oral administration (10 mg/kg) resulted in a peak plasma concentration (Cₘₐₓ) of 1.4 μg/mL, a time to peak concentration (Tₘₐₓ) of 1.2 h, a terminal half-life (t₁/₂) of 6.1 h, a volume of distribution (Vd) of 3.5 L/kg, and an oral bioavailability of 55%. Intravenous administration (5 mg/kg) showed a clearance (CL) of 0.42 L/h/kg [1]
- Tissue distribution: In rats, 2 hours after oral administration (10 mg/kg), SCH 563705 was distributed in the liver (tissue/plasma ratio = 2.9), lung (2.6), spleen (2.2), kidney (2.0) and synovial tissue (1.8); the concentration in brain tissue was lower (tissue/plasma ratio = 0.3) [1]
- In vitro metabolic stability: In human liver microsomes, the metabolic half-life of SCH 563705 was 78 min and the intrinsic clearance (CLint) was 16 μL/min/mg protein; in rat liver microsomes, t₁/₂ = 89 min [1]

Plasma protein binding: As determined by ultrafiltration, the plasma protein binding rate of SCH 563705 in human plasma was 93%, and in rat plasma it was 91%[1]. Acute toxicity: In rats, the oral LD₅₀ of SCH 563705 was >200 mg/kg. In a 7-day acute study, no significant toxicity (weight loss, seizures, death) was observed at doses up to 100 mg/kg[1]. Subchronic toxicity: In a 14-day repeated oral administration study (30 mg/kg/day) in mice, SCH 563705 did not cause significant changes in body weight, hematological parameters, or liver and kidney function[2].

[1]. C(4)-alkyl substituted furanyl cyclobutenediones as potent, orally bioavailable CXCR2 and CXCR1 receptor antagonists. Bioorg Med Chem Lett. 2007 Jul 1;17(13):3778-83.

[2]. Pharmacological targeting reveals distinct roles for CXCR2/CXCR1 and CCR2 in a mouse model of arthritis. Biochem Biophys Res Commun. 2010 Jan 1;391(1):1080-6.

Neutrophils and monocytes are abundant in the synovial fluid and tissues of patients with rheumatoid arthritis. Therefore, we investigated the role of small molecule chemokine receptor antagonists in blocking the migration of these cells in anti-collagen antibody-induced arthritis. Targeting neutrophil migration with the CXCR2/CXCR1 antagonist SCH563705 dose-dependently reduced clinical disease scores and claw thickness, and significantly alleviated inflammation and bone and cartilage degeneration based on histopathological and claw cytokine analysis. Conversely, targeting monocyte migration with the CCR2 antagonist MK0812 had no effect on arthritis disease severity. The pharmacodynamic activity of SCH563705 and MK0812 was validated by assessing their effects on peripheral blood monocyte and neutrophil populations. SCH563705 selectively reduced the frequency of peripheral blood neutrophils and led to an increase in the CXCR2 ligand CXCL1. MK0812 selectively reduced the frequency of peripheral blood mononuclear cells and led to an increase in CCR2 ligand CCL2. In this arthritis model, the significant effect of CXCR2/CXCR1 antagonism relative to CCR2 antagonism highlights the potential of targeting CXCR2/CXCR1 for the treatment of human arthritis. [2]

---

SCH 563705 is a potent, orally bioavailable CXCR1/CXCR2 antagonist belonging to the C(4)-alkyl-substituted furanylcyclobutenedione class of compounds. [1]
- Its core mechanism of action is to competitively block the binding of pro-inflammatory chemokines (CXCL8, CXCL1) to CXCR1/CXCR2, thereby inhibiting downstream signal transduction (calcium mobilization) and the recruitment of inflammatory cells (neutrophils, T cells) to the site of inflammation. [1][2] - Preclinical data support its potential therapeutic use in inflammatory arthritis (collagen-induced arthritis) and other inflammatory diseases, with its mechanism of action being the inhibition of synovial inflammation, joint damage, and the production of pro-inflammatory cytokines. [2] - The compound has favorable pharmacokinetic properties, including good oral bioavailability, moderate tissue distribution (targeting inflamed tissues such as the synovium), and low toxicity, supporting its potential for long-term oral administration. [1] - Compared with CCR2 antagonists, SCH 563705 showed significant anti-inflammatory effects in arthritis models, highlighting the specific role of CXCR1/CXCR2 in neutrophil-driven inflammation. [2]

C23H27N3O5

425.49

425.195

C, 64.93; H, 6.40; N, 9.88; O, 18.80

473728-58-4

10310100

White to off-white solid powder

1.29g/cm3

555.9ºC at 760 mmHg

290ºC

1.615

3.79

3

7

8

31

748

1

O=C(C(NC1=CC=CC(C(N(C)C)=O)=C1O)=C2N[C@H](CC)C3=CC(C(C)C)=CO3)C2=O

DGKQQEVYYPCMNE-OAHLLOKOSA-N

InChI=1S/C23H27N3O5/c1-6-15(17-10-13(11-31-17)12(2)3)24-18-19(22(29)21(18)28)25-16-9-7-8-14(20(16)27)23(30)26(4)5/h7-12,15,24-25,27H,6H2,1-5H3/t15-/m1/s1

3-[[3,4-dioxo-2-[[(1R)-1-(4-propan-2-ylfuran-2-yl)propyl]amino]cyclobuten-1-yl]amino]-2-hydroxy-N,N-dimethylbenzamide

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

---

Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

View More

Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

---

Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

View More

Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

---

Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

---

 (Please use freshly prepared in vivo formulations for optimal results.)